A difficulty of numerical analysis of breaking wave is caused from a difficulty of handling of free water surface. In late years tracking technique of free water surface develops rapidly, and some convincing water surface tracking is applied to a breaking wave phenomenon. New interface tracking techniques, such as a density-function method and a particle method, are introduced. A multi-phase flow model for a solid and liquid, or a liquid and gas, are also developed.Primal subjects are as follows : (1)a modeling of a gas liquid multi-phase flow ; (2)a modeling of structure-fluid interaction in a wave field ; (3)a modeling of a solid liquid multi-phase flow ; and (4)construction of a numerical wave flume.